JPH0411694A - Lubricating oil composition for buffer - Google Patents

Abstract

PURPOSE:To improve storability, wearing characteristics, low-temperature frictional properties and the like of a lubricating oil by adding a phosphorous ester, a phosphoric ester amine, a boron-containing dispersant for cleaning and a metal-deactivating agent to a base oil comprising a mineral oil and/or a synthetic oil. CONSTITUTION:A lubricating oil composition for buffer is prepared by adding 0.1 to 1.0wt.% of phosphorous ester having a 14 to 20C hydrocarbon group such as dioleyl phosphite, 0.1 to 1.0wt.% of a phosphoric ester amine having an 8 to 20C hydrocarbon group such as oleyl acid phosphate amine salt, 0.1 to 1.0wt.% of boron-containing dispersant for cleaning such as boron-containing succinamide, 0.01 to 0.3wt.% of a metal-deactivating agent such as benzotriazole and, optionally, additives such as viscosity index improver and antioxidant to a base oil comprising mineral oil and/or synthetic oil and having a viscosity of 1.5 to 3.0cSt at 100 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hydraulic oil composition used for various shock absorbers, and more specifically to a hydraulic fluid composition that is used particularly for suspension systems of automobiles and has excellent storage stability. The present invention relates to hydraulic fluid compositions.

[Conventional technology]

Various types of shock absorbers are used to effectively absorb vibrations, such as shock absorbers used in automobiles such as vehicle suspension systems, engine support systems, bumper support systems, and more generally door checkers. As such, hydraulic oil-filled shock absorbers are widely used.

In these shock absorbers, for example, in automobile shock absorbers, the three areas between the piston rod and the oil seal, between the piston rod and the piston guide bushing, and between the piston and the cylinder are particularly subject to wear and friction. ■ Chrome steel/rubber, ■ Chrome steel/polyvinylidene fluoride, ■ Mild steel/polyvinylidene fluoride (more specifically, polyvinylidene fluoride mixed with copper, lead, zinc, etc. as reinforcing agents), etc. body is used.

On the other hand, the shock absorber fluid filled in the shock absorber also contains anti-wear agents, oily agents (friction modifiers), etc. so that the shock absorber can withstand long-term use. For example, base oil containing zinc thiophosphate (anti-wear agent) and long-chain fatty acids (oily agent) (Japanese Patent Laid-Open No. 165996/1982) is known as a detergent and dispersant for internal combustion engines. There is one that improves abrasion resistance and low friction by blending a boron-containing detergent and dispersant with a phosphoric acid ester (Japanese Patent Laid-Open No. 58-45293).

However, in the former case, although zinc thiophosphate is an excellent anti-wear agent, it has a high coefficient of friction, and fatty acids used as an oil-based agent (usWIm formulation) are effective in reducing friction, but the buffer The disadvantage is that it corrodes bearing materials (especially composite materials containing lead) and accelerates wear. Moreover, the latter case is also not fully satisfactory from the viewpoint of friction coefficient characteristics, especially from the viewpoint of maintaining a low friction coefficient over a long period of time, and from the viewpoint of low-temperature friction characteristics.

Furthermore, as mentioned above, polyvinylidene fluoride contains copper, lead,
A composite containing reinforcing agents such as zinc is used as bearing metal, but if it is in contact with base oil at high temperatures (over 80°C) for a long time, copper etc. will be leached into the base oil. This can lead to oil deterioration and the bearing metal itself becoming brittle, but there is currently a lack of effective countermeasures.

[Problem to be solved by the invention]

The present invention has abrasion resistance and low coefficient of friction for materials used in shock absorber components, particularly in areas of high friction, and has good compatibility with rubber sealing materials, as well as copper and zinc in rod guide materials. An object of the present invention is to provide a hydraulic oil composition for shock absorbers which maintains a low coefficient of friction without eluting components such as tin, does not change in quality even during long-term operation, and has excellent low-temperature friction characteristics.

[Means to solve the problem]

The lubricating oil composition for shock absorbers of the present invention is characterized by blending a base oil consisting of mineral oil and/or synthetic oil with ■ a phosphorous acid ester ■ a phosphoric acid ester amine ■ a boron-containing detergent and dispersant ■ a metal deactivator. do.

In addition, the phosphorous ester has a hydrocarbon group having 14 to 20 carbon atoms, and the phosphoric acid ester amine has a hydrocarbon group having 8 to 20 carbon atoms. The present invention relates to a lubricating oil composition for shock absorbers.

Furthermore, the amount of the phosphorous acid ester is 0.1% to 1.0% by weight, and the amount of the phosphoric acid ester amine is 0.1% to 1.0% by weight based on the total amount of lubricating oil for shock absorbers. %, the amount of the boron-containing detergent and dispersant is 0.1% to 1.0% by weight, and the amount of the metal deactivator is 0.01% to 0.
, 3% by weight of the lubricating oil composition for a shock absorber.

The configuration of the present invention will be explained below.

Examples of the lubricating base oil in the present invention include various conventionally used phosphoric triesters, organic acid esters, mineral oils, silicone oils, olefin oligomers, polyoxyalkylene glycols, alkylene glycols, and derivatives thereof. It is preferable to use one having a viscosity of 1°5 cSt to 3,000°C at 100°C.

The components added to this base oil will be explained.

First, the phosphorous ester is -maximum (in the formula, R,, R2 is a saturated or unsaturated hydrocarbon group having 14 to 20 carbon atoms, such as an alkyl group, an aryl group, an alkyl-substituted aryl group, and may be the same or different). ) Examples include dilauryl hydrogen phosphite, distearyl hydrogen phosphite, dioleyl hydrogen phosphite, and the like.

If the number of carbon atoms in R1 and R3 is less than 14, the frictional force will be high, and the compatibility with rubber sealing materials, friction characteristics at low temperatures, and wear resistance will deteriorate. There is a problem with compatibility, and as a result, the frictional properties at low temperatures deteriorate, which is undesirable.

The phosphorous ester is added in an amount of 0.1% to 1.0% by weight based on the entire lubricating oil composition for shock absorbers, and if it is less than 0.1% by weight, it has no effect, and if it exceeds 1.0% by weight. compatibility with rubber sealing materials, and the frictional properties at low temperatures deteriorate.

The phosphoric ester amine added together with the phosphorous ester is -maximum % formula %) (wherein m and n each represent an integer of 1 or 2, R1 and R2 may be the same or different, and each carbon The number represents 8 to 20 saturated or unsaturated hydrocarbon groups, such as alkyl groups, aryl groups, and alkyl-substituted aryl groups.

If the number of carbon atoms in R1 is less than 8, the frictional force will be high, and if it exceeds 20, the frictional force will be high and the compatibility with the base oil will be lost, which is not preferable.

This phosphoric acid ester amine has a content of 0.0% based on the total amount of the lubricating oil composition for shock absorbers. It is good to contain 1% by weight to 1.0% by weight, and if it is less than 0.1% by weight, there is no effect of addition, and 1.0% by weight is less than 0.1% by weight.
If it exceeds % by weight, the frictional force will increase and the wear resistance will be poor.

Regarding phosphoric acid ester, it is not compatible with rubber sealants when blended alone and is not very desirable for blending into lubricating oil compositions for shock absorbers, but it should be blended to the extent that it does not deteriorate the rubber sealant. The content thereof is preferably 0.1% to 1.0% by weight based on the total amount of the lubricating oil composition.

The lubricating oil composition for shock absorbers of the present invention is superior to the case where a phosphorous ester and a phosphoric ester amine are added alone by blending the above-mentioned phosphorous ester and phosphoric ester amine to the base oil. It has excellent wear resistance, low friction, and compatibility with rubber sealing materials.

In addition, we have added a boron-containing cleaner to improve the elongation change rate of rubber sealing materials, disperse deteriorating substances such as sludge, improve apparent heat resistance, and improve abrasion resistance at high temperatures. Dispersants and metal deactivators are added.

The boron-containing detergent/dispersant is a product obtained by further reacting an alkyl-substituted succinic anhydride with a reaction product of an alkylene amine and a boron compound, which has been known as a detergent for internal combustion engines. Special Public Service 1977-8
013 Publication), a product obtained by reacting an alkylene amine with a reaction product of a hydrocarbon-substituted succinic anhydride and a boron compound (Japanese Patent Publication No. 1983-8014), a product obtained by reacting an alkylene amine with a reaction product of a hydrocarbon-substituted succinic anhydride (Japanese Patent Publication No. 1982-8014), a product obtained by reacting an alkenyl succinic anhydride with hydroxylation. A product obtained by reacting a primary amine with a boron compound (Japanese Patent Application Laid-Open No. 51-523
No. 81), a product obtained by reacting a boron compound with a product obtained by reacting an aromatic polycarboxylic acid, an alkenyl succinic acid, and a polyalkylene polyamine at a specific molar ratio (Japanese Patent Publication No. 81), 51-130408), a condensation product of amino alcohol, boric acid, and oxyethanecarboxylic acid (JP 54-87005), polyalkenyl succinic anhydride, polyalkylene glycol, secondary alkanolamine and Products obtained by sequentially reacting boron compounds, as well as those described in JP-A-55-157688 and US Pat. No. 2,568,472, can be used.

This boron-containing compound is preferably contained in a range of 0.1% to 1.0% by weight based on the total amount of lubricating oil, and if it is less than 0.1% by weight, there will be no addition effect and the compatibility with rubber sealing materials will be reduced. If it exceeds 1.0% by weight, the frictional force will increase.

In addition, metal deactivators are used to prevent components such as copper, zinc, tin, and lead contained in guide bushes and piston band materials from being eluted into the lubricating oil by phosphoric acid esters and increasing the amount of wear. It is added to. When only phosphoric esters are added, wear resistance deteriorates and corrosive wear occurs, especially at high temperatures (160°C), but the addition of this metal deactivator improves the performance compared to when phosphoric esters are added alone. In comparison, this defect has been suppressed and it has achieved excellent wear resistance.

Examples of metal deactivators used in the buffer lubricating oil composition of the present invention include benzotriazole, benzotriazole derivatives, benzothiazole, pendithiazole derivatives, triazole, triazole derivatives, dithiocarbamates, dithiocarbamate derivatives, indazole, indazole Derivatives etc. can be used.

The proportion of the metal deactivator used is 0.005% by weight to 0.00% by weight based on the total amount of the lubricating oil composition. 3% by weight, preferably 0.
It is preferable to use 0.01% to 0.2% by weight. Added amount is 0
．． If it is less than 0.005% by weight, there is no effect of addition, and if it exceeds 0.3% by weight, the frictional force becomes high, which is not preferable.

Each component in the lubricating oil composition for shock absorbers of the present invention has been described above, but in addition to these, viscosity index improvers, antioxidants, etc. can be added as appropriate.

[Action and effect of the invention]

The lubricating oil composition for shock absorbers of the present invention contains a combination of a specific phosphorous ester and a specific phosphoric ester amine as phosphoric esters, and also contains specific amounts of a boron-containing compound and a metal deactivator, respectively, for lubricant. By containing it in base oil, it has excellent wear resistance and low friction properties as a lubricant for shock absorbers, as well as compatibility with rubber seal materials and good friction properties over a wide range of operating temperatures. What we have and what we can do.

The present invention will be explained below with reference to Examples.

[Example 1] Frictional force was measured for various shock absorber lubricating oil compositions described below using a monotube shock absorber for automobiles. The frictional force measurement was performed by moving the rod of a monotube shock absorber up and down at high speed, and using the force required to move the rod up and down as the frictional force.The results are shown in the table below.

The buffer operating conditions in this case are as follows.

Operating temperature 25℃ Stroke ±20mm Vibration frequency L H.

Lateral load OKg, 10Kg, 30Kg gas filling pressure 5. 0 Kg/cm' Also, the wear resistance was measured using a twin tube shock absorber. Lubricating oil was applied for lubrication between cylinder and piston, rod and seals and guides.

The operating conditions in this case are as follows.

Stroke: ±30mm Stroke speed: 200 times/min Lateral load: 50Kg Wear resistance was determined by observing the appearance of the rod after the test and observing the occurrence of cloudiness and scratches.The results are shown in the table below. In the table below, ○ indicates no change, △ indicates cloudiness due to slight scratches, and X indicates large scratches.

Furthermore, compatibility with the rubber sealing material was determined by observing the surface of the rubber sealing material after the test and determining the size of bubbles generated on the surface. The results are shown in the table below, in which no bubbles are indicated by ◯, and large bubbles are indicated by △.

Furthermore, the low-temperature friction characteristics are determined by assuming that the operating temperature of the above-mentioned monotube shock absorber is 0° C. In the table below showing the results, the case without stick-slip is indicated by ◯, and the case with stick-slip is indicated by △.

The solubility with the base oil was determined by a long-term (one month) storage test.The table below shows the results.In the case of transparency, ○, in the case of slight cloudiness, △, and in the case of precipitation, Indicated by X.

Next, regarding each component in the lubricating oil composition prepared in this example, the following were used unless otherwise specified in each table.

■Base oil: Mineral oil (100 neutral) ■Phosphate esters: - Phosphite: dioleyl phosphite ° Phosphoric acid ester nioleyl acid phosphate - Phosphoric acid ester Amine: oleyl acid phosphate amine salt ■Boron-based detergent and dispersant: Boron-based succinate Acid γ amide ■Metal deactivator: benzotriazole ■Other additives: phenyl-α-naphthylamine, silicone oil Add the above ingredients to the base oil in the amounts listed in the table below. Inventive sample oils and comparative oils were prepared.

Next, the results of each test described above are shown.

First, Table 1 shows the results of testing the effect of phosphate ester amine in different amounts in the composition.

Table 2 shows the results of testing the effects of phosphorous esters and phosphoric esters with different amounts added.

Table 3 shows the results when a phosphorous ester having a straight alkyl group having the number of carbon atoms shown in the table was used in place of the oleyl group in dioleyl phosphite.

Table 4 shows the results when a phosphoric ester amine having a different number of carbon atoms was used in place of the oleyl group in the phosphoric ester amine.

Table 5 shows the results when the amount of boron-based detergent and dispersant added was varied.

Table 6 shows the results when the amount of metal deactivator added was varied.

Further, the proportion of each component in the table below is % by weight, and the unit of frictional force is Kg 7cm2.

(Margin below) No. table No. table No. table No. table No. table No. table The following can be seen from the above tables.

First, Table 1 shows that the comparative oils that do not contain phosphate ester amines have good compatibility with rubber sealing materials, low-temperature friction properties,
The abrasion resistance is poor, and even if the sample oil is similar to the present invention, if the amount of phosphate ester amine used exceeds 1.0% by weight,
It can be seen that while the friction force and wear resistance are poor, the sample oil of the present invention is excellent in low friction force, compatibility with rubber sealing materials, friction characteristics at low temperatures, and wear resistance.

In addition, as shown in Table 2, those that do not contain diphosphorous ester but contain phosphoric acid ester have high frictional force, poor compatibility with rubber sealing materials, and poor wear resistance. It can be seen that the sample oil deteriorates as it is used, whereas the sample oil of the present invention has excellent low frictional force, compatibility with rubber sealing materials, low-temperature friction characteristics, and wear resistance.

Furthermore, as shown in Table 3, the number of carbon atoms in the substituted alkyl group in the second phosphorous ester of the present invention is 14 to 2.
It can be seen that those with a value of 0 are excellent in low frictional force, compatibility with rubber sealing materials, low-temperature friction characteristics, and wear resistance.

In addition, as shown in Table 4, phosphate ester amine salts with substituted alkyl groups having 8 to 22 carbon atoms have low frictional force, compatibility with rubber sealing materials, low-temperature friction properties, and wear resistance. It can be seen that they are superior in both sex.

Furthermore, as shown in Table 5, there are those that do not contain boron-containing detergent and dispersants, and those that do contain boron-containing detergents and dispersants, and those that contain boron-containing detergents and dispersants, but the content is 1.0.
It can be seen that if the content exceeds % by weight, the frictional force is high, and if it does not contain it, the compatibility with the rubber sealing material is even worse.

Furthermore, it can be seen that the frictional force is increased in those that do not contain a metal deactivator and those that contain a metal deactivator in a content exceeding 0.3% by weight.

Applicant: Tomoen Co., Ltd.

Claims (1)

[Scope of Claims] [1] Base oil consisting of mineral oil and/or synthetic oil contains (1) phosphorous ester (2) phosphoric ester amine (3) boron-containing detergent and dispersant (4) metal deactivator. A lubricating oil composition for a shock absorber, characterized by comprising: [2] The phosphorous ester has a hydrocarbon group having 14 to 20 carbon atoms, and the phosphoric ester amine has a hydrocarbon group having 8 to 20 carbon atoms.
The lubricating oil composition for shock absorbers according to claim 1, having a hydrocarbon group of [3] The blending amount of the phosphorous ester is 0.1% to 1.0% by weight, and the blending amount of the phosphoric acid ester amine is 0.1% to 1.0% by weight based on the total amount of lubricating oil for shock absorbers. %, the amount of the boron-containing detergent and dispersant is 0.1% to 1.0% by weight, and the amount of the metal deactivator is 0.01% to 0.0% by weight.
The lubricating oil composition for shock absorbers according to claim 1 or 2, wherein the content is 3% by weight.